Method for oxyacetylene-cutting a piece of steel and device for carrying out this method

ABSTRACT

The invention relates to apparatus for oxygen cutting pieces of steel. The cutter and trimmer members ( 5, 10 ) are positioned in such a manner that the cutting jet ( 6 ) is applied to the top face ( 1.1 ) of the piece ( 1 ) in a substantially vertical direction, while the trimming jet ( 12 ) is applied to the bottom face ( 1.2 ) of said piece in an oblique direction that remains pointed towards the outlet point ( 14 ) of the cutting jet ( 6 ), simultaneous cutting and trimming being performed by moving the cutter and trimmer members ( 5, 10 ) horizontally in synchronous manner. A sprayer member ( 11 ) is also provided for spraying fluid during the cutting process towards molten particles in order to reduce fume emissions.

The present invention relates to a method and to apparatus for oxygencutting pieces of steel such as slabs, sheets, billets, and blooms.

The technological background is illustrated by document EP-A-0 639 416which describes a two-line oxygen-cutting installation, each linecomprising a moving carriage for a pendular type oxygen-cutter torch.Reference can also be made to document U.S. Pat. No. 2,820,420 whichdescribes an oxygen-cutting torch cantilevered-out on a carriage thatcan be moved horizontally, and to document WO-A-96/20818 which describesa traveling crane carrying a telescopically-extendible vertical workingarm.

Reference can also be made to documents U.S. Pat. No. 2,288,026 and U.S.Pat. No. 2,541,344.

Oxygen-cutting pieces of steel, and more particularly in steelmakingslabs, sheets, billets, and blooms, generally forms unburnt molten metalresidues at the outlet surface of the cutting jet, with a fraction ofthe residue that is not ejected into the surrounding atmosphere by thecutting jet sticking to the outlet lips of the cut slot, and with thishappening over the entire length of the slot so as to form a cuttingbead or rim. As a result, at the end of the cutting process, each edgeof the slot on its cutting jet outlet side presents a bead which isconstituted by a mixture of the basic metal together with iron oxide.This unwanted bead adheres strongly to the bodies of the cut-apartpieces, and it is necessary to provide an additional operation ofremoving such beads which are of greater or lesser size depending on thegrades of steel involved, the speed of cutting, and the types andadjustments of the oxygen-cutter torch. The cutting beads are generallyremoved by trimming, either manually using a blow torch, a chisel, or agrinder, or indeed mechanically by means of an appropriate machine. Inall cases that involves an additional finishing operation which impliesextra cost that penalizes production cost price.

To solve that problem, proposals have already been made for a method ofoxygen cutting a piece of steel in which a cutter member is positionedin such a manner that the cutting jet is directed towards a first faceof the piece to be cut and a trimmer member is positioned in such amanner that the trimming jet is directed to a second face, opposite fromthe first, towards the outlet point of the cutting jet so as to performtrimming simultaneously on the cutting bead as it forms on said secondface, with the positioning of the cutter and trimmer members being suchthat the cutting jet is applied to the top face of the piece in asubstantially vertical direction, while the trimming jet is applied tothe bottom face of said piece in an oblique direction that remainspointing towards the outlet point of the cutting jet, simultaneouscutting and trimming being performed by moving the cutter and trimmermembers horizontally in synchronous manner. In this respect, referencecan be made to documents EP-A-0 017 807 (& U.S. Pat. No. 4,336,078) andDE-A-20 43 539.

With continuously cast billets, combined oxygen-cutting and trimmingapparatus has already been proposed in which a cutter member ispositioned in such a manner that the cutting jet is directed towards afirst face of the piece to be cut and a trimmer member is positioned sothat the trimming jet is directed towards a second face opposite to thefirst, towards the outlet point of the cutting jet so as to performsimultaneous trimming of the cutting bead as it forms on said secondface. Such a process is described in document WO-A-99/16570. In thatmethod, the cutter member and the trimmer member are positioned bytaking a direct reference from the continuously cast billet by using amoving clamp. Once the reference has been taken, the cutter member andthe trimmer member are lowered parallel to the side faces of the billetso as to cut it progressively downwards by horizontally engaging one ofthe side faces of the billet while simultaneously trimming the cuttingbead that forms on the other side face by attacking said other side facein a direction that is continuously directed downwards. Thus, in thattechnique, the cutting jet is horizontal and it is applied to one of theside faces of the billet, and this applies throughout the cuttingprocess.

That technique is indeed advantageous for oxygen cutting continuouslycast billets, however it remains very limited because of the way inwhich the oxygen cutting is unsuitable for use on other steel products.

Firstly, it can be observed that that method is not adaptable to cuttingslabs or other products of great width. Since the oxygen cutting isperformed horizontally, such a configuration is out of the question whenthe product to be cut is of great width, as is the case for slabs orsheets. It would be unrealistic to imagine clamping the product that isto be cut by means of the reference clamps, and above all making anoxygen-cutting jet of sufficient power to perform cutting across theentire width of the product.

That technique is also unsuitable for splitting operations, i.e. cuttingproducts in the lengthwise direction, which operation is often performedon slabs or sheets. This unsuitability is both physical with continuouscast slabs, and economic with slabs and sheets outside continuouscasting because of the need for expensive handling of the products orbecause of the size and the complexity of installations capable ofimplementing that technique.

In all cases, in practice it is found that large amounts of fumes arepresent in the outlet zone of the cutting jet, with these fume emissionsbeing generated by the post-combustion of unburnt molten metal residuesthat are ejected by the cutting jet and by the trimming jet.

The invention seeks to design an oxygen-cutting technique that makes itpossible to avoid the above-mentioned drawbacks and/or limitations.

Thus, an object of the invention is to provide a method of oxygencutting a piece of steel and apparatus for implementing the method whichare capable of cutting a very wide variety of types of pieces of steelin regular manner without leaving any cutting bead, while simultaneouslyreducing fume emissions, and to do so regardless of the width of theproduct that is to be cut. The looked-for technique must, in particular,be capable of performing splitting operations under good conditions bothtechnically and economically.

According to the invention, this problem is resolved by a method ofoxygen cutting a piece of steel, in which a cutter member is positionedin such a manner that the cutting jet is directed towards a first faceof the piece to be cut and a trimmer member is positioned in such amanner that the trimming jet is directed towards a second face, oppositefrom the first face, towards the outlet point of the oxygen-cutting jetso as to perform trimming simultaneously on the cutting bead as it formson said second face, with the positioning of the cutter and trimmermembers being such that the cutting jet is applied to the top face ofthe piece in a substantially vertical direction, while the trimming jetis applied to the bottom face of said piece in an oblique direction thatremains pointing towards the outlet point of the cutting jet,simultaneous cutting and trimming being performed by moving the cutterand trimmer members horizontally in synchronous manner, the method beingremarkable in that a sprayer member is positioned beneath the piece insuch a manner that a fluid jet is sprayed during the cutting processtowards the molten particles ejected by the cutting jet so as to reducefume emission.

According to an advantageous characteristic, the spray jet is directedtowards the zone at the top of the parabolic trajectory followed byfalling molten particles.

It is then preferable for the sprayer member to be moved horizontallysynchronously with the cutter and trimmer members, the cutting,trimming, and spray jets remaining in a common vertical plane.

It is also advantageous to make provision for the sprayer member to becarried by the support for the trimmer member passing through the cutslot.

Also advantageously, the support for the trimmer and sprayer members isset into vertical vibration during the cutting process. Such verticalvibration facilitates progress of the support passing through the cutslot.

The invention also provides apparatus for implementing theabove-specified oxygen-cutting method, the apparatus being remarkable inthat it comprises a carriage that is horizontally movable on associatedrails, said carriage carrying supports for a cutter member and for atrimmer member, which supports overlie the piece to be cut, the supportfor the trimmer member including a thin blade for passing through thecut slot, said thin blade which supports the trimmer member alsosupporting a fluid sprayer member.

The presence of the thin blade is extremely advantageous insofar as itmakes it possible to organize support for the cutter, trimmer, andsprayer members from above the piece that is to be cut, thereby leavingcompletely empty the space that is situated beneath said piece. Inaddition, because of its rigidity, the thin blade makes it possible toguarantee that the various supported members are properly positionedrelative to one another, both in terms of position and in terms ofinclination.

Advantageously, the trimmer and sprayer members are both mounted at theend of the thin blade, each being inclined upwards at a respectivepredetermined angle.

The fluids necessary for the trimmer and sprayer members can be fed bymeans located beneath the piece that is to be cut. Nevertheless, inorder to avoid the drawbacks to be expected from projected splashes ofmolten metal, it is advantageous to provide for feeding to take placefrom above the piece.

To this end, and in accordance with another advantageous characteristic,the thin blade is hollow for feeding the fluid(s) required.

It is also advantageous to provide for the thin blade to be coupled to avibrator capable of imparting small-amplitude vibration in a verticaldirection, thereby avoiding any risk of metal droplets sticking in theslot, since that could impede proper progress of the thin blade duringthe cutting process.

Also preferably, the supports for the cutter, trimmer, and sprayermembers are individually adjustable in position in a vertical direction.These individual adjustments are important to make it possible to adaptto pieces for cutting having a variety of thicknesses.

In a particular embodiment, the carriage moves along the piece andcarries a cantilevered-out beam on which the supports for the cutter,trimmer, and sprayer members are mounted via a sleeve slidably mountedon said beam.

In a variant, when oxygen cutting a continuous casting, it isadvantageous to provide for the carriage to move above the casting andto carry a moving clamp for clamping onto said casting via its sidefaces, said carriage being capable of receiving a removable framecarrying a slider that is movable across the casting direction, whichslider carries the supports for the cutter, trimmer, and sprayermembers. This makes it possible in particular to use the installationdescribed in above-cited document WO-A-99/16570 by replacing thehorizontal oxygen-cutting jet cutter and trimmer unit with another unitthat is secured to the removable frame to provide the vertical cuttingjet in accordance with the invention.

Other characteristics and advantages of the invention appear moreclearly in the light of the following description and the accompanyingdrawings relating to particular embodiments, and referring to thefigures, in which:

FIG. 1 is a diagram of an installation for implementing theoxygen-cutting method of the invention, in a first embodiment having twoseparate carriages organized to move horizontally in synchronous manner;

FIG. 2 is a diagrammatic view showing another variant implementation ofthe oxygen-cutting method of the invention in which the support for thetrimming and spraying members passes through the cut slot;

FIG. 3 shows, on a larger scale, the members used in the FIG. 2 variant,with a thin blade which supports the trimming and spraying members;

FIG. 4 is an end view of the components of FIG. 3 showing more clearlyhow the thin blade passes through the cut slot;

FIG. 5 is a section on V—V of FIG. 3 showing the fluid-passing ductsinside the thin blade;

FIGS. 6 and 7 are respectively an end view and a section view of anembodiment of the apparatus for implementing the method, using acarriage which moves laterally along the piece which is to be cut; and

FIGS. 8 and 9 are an elevation view and an end view respectively ofanother variant of the apparatus in which the carriage travels over acontinuous casting and carries a moving clamp for holding the casting.

FIG. 1 shows a piece of steel such as a slab, a billet, or a bloom thatis being cut using the oxygen-cutting method of the invention. The piece1 to be cut presents a top face 1.1 and a bottom surface 1.2, and itrests horizontally on supports (not shown in the figure). A carriage 2is movably mounted on rails 3 by means of wheels 4, and the carriagecarries a cutter member 5 which is an oxygen-cutting torch by means of arigid support 16. The cutter member 5 is positioned in such a mannerthat the oxygen-cutting jet referenced 6 is applied to the top face 1.1of the piece 1 in a direction that is substantially vertical. Beneaththe piece 1, another carriage 7 is provided which is mounted to move onrails 8 via associated wheels 9. This carriage 7 carries a trimmermember 10 via a support 17, which trimmer member is positioned in such amanner that the trimming jet referenced 12 is applied to the bottom face1.2 of the piece 1 in an oblique direction that remains pointed towardsthe outlet point referenced 14 of the cutting jet 6.

In this embodiment, which is intended more particularly for a slittingoperation, simultaneous cutting and trimming are performed by moving thecutter 5 and the trimmer 10 horizontally in synchronous manner byappropriately controlling the movement of the associated carriages 2 and7. It is important to observe that the trimming is performed by a torchoperating in “ceiling” mode, i.e. from underneath a piece that is beingcut, which is highly advantageous compared with traditional systemsusing a horizontal oxygen-cutting jet, such as that disclosed inabove-cited document WO-A-99/16570. Ceiling mode trimming isparticularly effective insofar as this configuration is highly favorablefor ensuring that the trimmed-off beads become detached and fall awayeasily and quickly under the effect of the forces of gravity. Inaddition, since the trimmer 10 is behind the cutting jet, there is noobstacle in the immediate vicinity to disturb downstream ejection ofparticles.

In FIG. 1, it should also be observed that a sprayer member 11 ispresent mounted on an associated support 18 carried by the carriage 7which supports the trimmer member 10.

Thus, the sprayer 11 is positioned beneath the piece 1 in such a mannerthat a jet of fluid 13 is sprayed during the cutting process onto themolten particles ejected by the cutting jet 6 so as to reduce fumeemissions. In practice, the cutter 5, the trimmer 10, and the sprayer 11are arranged in such a manner that the three corresponding jetsrespectively referenced 6, 12, and 13 are all contained in a commonvertical plane throughout the cutting process. The sprayed fluid whichcan be water or oxygen acts as an extinguishing fluid with respect toincandescent particles. By spraying cold fluid in this manner on thepost-combustion particles of steel coming from the cutting and trimmingjets, the volume of fumes emitted can be reduced considerably.

In the above embodiment, the supports firstly for the cutter andsecondly for the trimmer and sprayer are arranged on opposite sides ofthe piece 1 that is to be cut. This requires good synchronization to beorganized in controlling the advance of the two carriages 2 and 7 so asto ensure that the jets 12 and 13 are always properly directed relativeto the outlet from the cutting jet 6 situated at the leading end of thecut slot referenced 1.3. Nevertheless, in a variant embodiment, theinvention provides for the support to be carried from the same side ofthe piece that is to be cut, in particular by being disposed above saidpiece.

This variant is described below and is shown diagrammatically in FIG. 2.

In accordance with the invention, displacement of the cutter 5, thetrimmer 10, and the sprayer 11 is synchronized by arranging for all ofthe supports coupled to said members to be disposed on the same side ofthe piece, with one of said supports extending through the cut slot 1.3.Specifically, the supports 17 and 18 for the trimmer 10 and the sprayer11 are united to form a common support in the form of a blade 20 whichis thin enough to pass through the cut slot 1.3. Thus, the support 16and 20 for the cutter 5 and for the trimmer 10 are disposed above thepiece 1, and it is the support 20 for the trimmer 10 which passesthrough the cut slot 1.3. Naturally, it is possible to provide theinverse arrangement in which the carriage 2 does not overlie the piece1, but is located underneath it. Nevertheless, it is more advantageousto use this overlying disposition since it makes it possible for thespace situated beneath the piece that is to be cut to be left completelyempty.

The rigid support provided by the blade 20 which passes through the cutslot 1.3 makes it possible to avoid performing any complex operation ofsynchronizing two separate carriages, and it ensures that the threemembers 5, 10, and 11 are permanently positioned relative to oneanother, and thus that the three associated jets 6, 12, and 13 arealways properly positioned.

As in the FIG. 1 variant, the thin blade 20 carries a sprayer 11 whosejet 13 is directed towards the molten particles ejected by the cuttingjet 6. It is advantageous for the spray jet 13 to be directed towards azone referenced 15 corresponding to the top of the parabolic trajectoryfollowed by the falling molten particles. The particles are initiallysubjected to kinetic energy by the cutting jet 6 and the trimming jet 12so their trajectory presents a point of inflection having a horizontaltangent prior to beginning the corresponding parabolic portion solelyunder the influence of the forces of gravity. This point of inflection,which corresponds to the above-mentioned zone 15, constitutes an idealtarget for the spray jet since the particles are then traveling atsubstantially zero speed.

FIGS. 3 to 5 show more clearly how the cutter 5, trimmer 10, and sprayer11 are arranged together with their respective jets 6, 12, and 13. Thethin blade 20 supporting the members 10 and 11 is shown in section. Inthis case, the thin blade 20 supporting the members 10 and 11 is hollowso as to feed the required fluids. There can thus be seen two ducts 21and 22 reaching the inside spaces 23 and 24 of the members 10 and 11 soas to deliver the corresponding fluids which are fed in via inlets 25and 26. The trimming fluid is generally oxygen, but it is also possibleto provide water or any other equivalent fluid. For spraying, it isgenerally suitable to use cold water. It is advantageous to observe thatthe presence of cold water in the thin blade is advantageous for coolingthis member during the cutting process and after the process hasterminated.

Both the trimmer 10 and the sprayer 11 are mounted at the end of thethin blade 20, and each of them is upwardly tilted at a respectivepredetermined angle. These angles are selected to optimize trimming forthe jet 12 which points towards the outlet point 14 of the cutting jet6, and to optimize spraying for the jet 13 which is directed towards thetop of the parabolic trajectory followed by the falling moltenparticles. In practice, the supports for the cutter 5, trimmer 10, andsprayer 11 are vertically adjustable in position. By individuallyadjusting the cutter 5 and the blade 10 it is possible to adapt theapparatus to cutting pieces of different thicknesses.

It is also advantageous to provide for the thin blade 20 to be coupledto a vibrator suitable for generating vibrations of small amplitude in avertical direction. Such a vibrator (not shown) is preferably integratedin the support for the thin blade 20. Setting the thin blade 20 intovertical vibration during the cutting process has the effect of shearingany metal drops that might stick to the thin blade in the slot. Thisensures that the advance of the members 5, 10, and 11 is not disturbedduring the cutting process.

A particular embodiment of the apparatus for implementing the method ofthe invention is described below with reference to FIGS. 6 and 7.

The slab 1 to be cut is positioned in a splitting area 17 fitted with atrench 18 into which the cutting jet penetrates. A self-propelledcarriage 102 travels on its wheels 104 on a track 103 alongside thepiece 1, parallel to the longitudinal axis of the slab. The carriage 102carries a cantilevered-out beam or bracket 105, of rectangular sectionin this case, which in turn slidably carries a sleeve 106 above the slabthat is to be cut. The sleeve 106 can be locked in position on thebracket 105 by means of a screw 107. As can be seen more clearly in FIG.7, the sleeve 106 supports the supports 16 and 17 associatedrespectively with the cutter 5 and with the trimmer and the sprayer 10,11. These supports 16, 17 are releasably fixed to the sleeve 106 withvertical adjustment enabling the corresponding members to be positionedappropriately. The supports 16 and 17 slide vertically in a plane whichis the plane containing the three jets 6, 12, and 13. Each support 16,17 can be set at the desired height by means of an associated screw 108,109. FIG. 7 shows how the relative positions of the cutting jet 6, thetrimming jet 12, and the spray jet 13 can be accurately positionedgeometrically relative to the slab that is to be cut. There can also beseen pipes for feeding the various members, which pipes are connected tothe tops of the supports 16 and 17. There can thus be seen pipes 110,111 serving to feed the cutter with heating and cutting oxygen and withfuel gas, and pipes 112, 113 serving to feed the trimmer and the sprayerwith trimming oxygen or water, and with water for extinguishingpost-combustion.

Another embodiment is described below with reference to FIGS. 8 to 10,this embodiment corresponding to equipment for an oxygen-cutting machineof the type described in document WO-A-99/16570. That prior art machine,intended more particularly for cutting a piece that is being castcontinuously, comprises a carriage fitted with a moving clamp forclamping onto the casting via its side faces. In the prior art machine,as a variant of the pendular cutting system that does not providetrimming of the cutting bead, provision is made for a chassis systemcarrying a cutter member and a trimmer member arranged in such a mannerthat the cutting jet is horizontal. It then suffices for that cutterunit to be replaced by another unit arranged in accordance with theinvention so as to perform cutting by means of a vertical cutting jet,with trimming and spraying taking place on the underside of thecontinuous casting. This makes it possible to take advantage of numerousmembers that already exist on the machine that is already in use.

The figures are diagrams showing the various components of the machine,and for further details reference can be made to document WO-A-99/16570.

There can be seen a carriage 202 moving on wheels 203 running onassociated rails 204 overlying the product to be cut 1. The two arms 205of a moving clamp are pivotally mounted on sleeves 206 secured to thecarriage 202 and they can be moved towards or away from each other byactuating on an associated actuator 207. The continuous casting 1travels on support rollers A and when the moving clamp 205 is clamped,the carriage 202 is entrained by the movement of the piece to be cut.This guarantees that its advance is synchronized with that of theproduct. A motor-driven feeler 208 comes into contact with the product,thereby starting the oxygen-cutting sequence implemented by theassociated cutter. In this case, the horizontal pendular cutter orcutter member using an oxygen-cutting jet as is conventionally used hasbeen replaced by an oxygen-cutting unit in accordance with theinvention.

There can be seen a removable frame 220 fixed to the structure of thecarriage 202 by bolts 221. The removable frame 220 carries horizontalslideways 223 between which a slider 222 moves horizontally. The slider222 is driven by a horizontal wormscrew 224 coupled to the outlet shaftof a drive motor 225. The slider 222 carries a sleeve 226 having thesupports 16 and 17 mounted thereon which are respectively associatedwith the cutter 5 and with the trimmer and sprayer 10, 11. The heightsof the supports 16 and 17 can naturally be adjusted and they can belocked in position using associated bolts 227.

Once the supports 16 and 17 are in place enabling the cutting jet andthe trimming jet to meet at a point which is level with the bottom faceof the slab to be cut, it suffices to actuate the drive motor 225 tocause the members 5, 10, 11 to move horizontally, thereby proceedingwith a stage of cutting with simultaneous trimming and fluid spraying soas to reduce the amount of fume emission. The slider 222 is moved acrossthe casting direction with great precision so that it is guaranteed thatthe casting bead is properly removed from the bottom face of the slab.The screw-and-nut system constituted by the wormscrew 224 and the slider222 ensures that the various above-mentioned members advance regularlyand accurately.

This provides a method and apparatus for oxygen cutting that enables thecasting bead and post-combustion projections to be treated effectivelyfor the purposes of fume reduction, and enables this to be performed onany type of piece that is to be cut, regardless of its width.

The invention is not limited to the embodiments described above, but onthe contrary covers any variant using equivalent means to reproduce theessential characteristics specified above.

What is claimed is:
 1. A method of oxygen cutting a piece of steel, inwhich a cutter member (5) is positioned in such a manner that thecutting jet (6) is directed towards a first face of the piece to be cut(1) and a trimmer member (10) is positioned in such a manner that thetrimming jet (12) is directed towards a second face, opposite from thefirst face, towards the outlet point (14) of the oxygen-cutting jet soas to perform trimming simultaneously on the cutting bead as it forms onsaid second face, with the positioning of the cutter and trimmer members(5, 10) being such that the cutting jet (6) is applied to the top face(1.1) of the piece (1) in a substantially vertical direction, while thetrimming jet (12) is applied to the bottom face (1.2) of said piece inan oblique direction that remains pointing towards the outlet point (14)of the cutting jet (6), simultaneous cutting and trimming beingperformed by moving the cutter and trimmer members (5, 10) horizontallyin synchronous manner, wherein a sprayer member (11) is positionedbeneath the piece (1) in such a manner that a fluid jet (13) is sprayedduring the cutting process towards the molten particles ejected by thecutting jet (6) so as to reduce fume emission, wherein the sprayermember (11) is carried by the support (20) for the trimmer member (10)passing through the cut slot (1.3).
 2. A method according to claim 1,wherein the spray jet (13) is directed towards the zone (15) at the topof the parabolic trajectory followed by falling molten particles.
 3. Amethod according to claim 1, wherein the sprayer member (11) is movedhorizontally synchronously with the cutter and trimmer members (5, 10),the cutting, trimming, and spray jets (6, 12, 13) remaining in a commonvertical plane.
 4. A method according to claim 1, wherein the support(20) for the trimmer and sprayer members (10, 11) is set into verticalvibration during the cutting process.
 5. An apparatus for implementing amethod of oxygen cutting a piece of steel, in which a cutter member (5)is positioned in such a manner that the cutting jet (6) is directedtowards a first face of the piece to be cut (1) and a trimmer member(10) is positioned in such a manner that the trimming jet (12) isdirected towards a second face, opposite from the first face, towardsthe outlet point (14) of the oxygen-cutting jet so as to performtrimming simultaneously on the cutting bead as it forms on said secondface, with the positioning of the cutter and trimmer members (5, 10)being such that the cutting jet (6) is applied to the top face (1.1) ofthe piece (1) in a substantially vertical direction, while the trimmingjet (12) is applied to the bottom face (1.2) of said piece in an obliquedirection that remains pointing towards the outlet point (14) of thecutting jet (6), simultaneous cutting and trimming being performed bymoving the cutter and trimmer members (5, 10) horizontally insynchronous manner, wherein a sprayer member (11) is positioned beneaththe piece (1) in such a manner that a fluid jet (13) is sprayed duringthe cutting process towards the molten particles ejected by the cuttingjet (6) so as to reduce fume emission, the apparatus comprising acarriage (2; 102; 202) that is horizontally movable on associated rails,said carriage carrying supports (16, 17) for a cutter member (5) and fora trimmer member (10), which supports overlie the piece to be cut (1),the support (17) for the trimmer member (10) including a thin blade (20)for passing through the cut slot (1.3), said thin blade (20) whichsupports the trimmer member (10) also supporting a fluid sprayer member(11).
 6. Apparatus according to claim 5, wherein the trimmer and sprayermembers (10, 11) are both mounted at the end of the thin blade (20),each being inclined upwards at a respective predetermined angle. 7.Apparatus according to claim 5, wherein the thin blade (20) is hollowfor feeding the fluid(s) required.
 8. Apparatus according to claim 5,wherein the thin blade (20) is coupled to a vibrator capable ofimparting small-amplitude vibration in a vertical direction. 9.Apparatus according to claim 5, wherein the supports (16, 17) for thecutter, trimmer, and sprayer members (5, 10, 11) are individuallyadjustable in position in a vertical direction.
 10. Apparatus accordingto claim 5, wherein the carriage (102) moves along the piece (1) andcarries a cantilevered-out beam (105) on which the supports (16, 17) forthe cutter, trimmer, and sprayer members (5, 10, 11) are mounted via asleeve (106) slidably mounted on said beam.
 11. Apparatus according toclaim 5, for oxygen cutting a continuous casting, wherein the carriage(202) moves above the casting (1) and carries a moving clamp (205) forclamping onto said casting via its side faces, said carriage beingcapable of receiving a removable frame (220) carrying a slider (222)that is movable across the casting direction, which slider carries thesupports (16, 17) for the cutter, trimmer, and sprayer members (5, 10,11).